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Institute of Behavioural Sciences, Semmelweis University, Budapest, Hungary
Experimental evidence supports the relationship between infant attachment and limbic system functioning. Adult attachment was shown to be related to individual differences in dream recall and dream content, while evidence supports the leading role of the limbic system in REM sleep cortical activation. However, there is no direct evidence supporting the relationship between adult attachment and REM sleep physiology. Pharmacological activation of the limbic system increases high frequency EEG activity in adult humans. We aimed to reveal the relationship between REM sleep high frequency EEG activity and attachment styles in adult humans. We hypothesized that attachment insecurity is related to enhanced high frequency EEG activity during REM sleep. Artefact-free REM sleep EEG of the 2nd night of sleep laboratory recordings (0.1–110 Hz, 50 Hz notch filter; 249 Hz/ch) were analyzed by FFT (4 s, Hanning-tapered, zero-padded) in 13 healthy volunteers. Average power spectra of gamma (30–50 Hz), omega1 (50–70 Hz) and omega2 (70–110 Hz) activities were correlated with factor scores of the Relationship Scales Questionnaire designed to assess adult attachment. In order to control for invisible muscular artefacts, the above mentioned analyses were performed for a submental EMG derivation too. Attachment avoidance correlated negatively with omega1 and omega2 activity in 7 and 13 derivations respectively. Correlations with omega 2 activity largely survived Bonferroni correction (P3: r = 0.83, P = 0.0003; C3: r = 0.81, P = 0.0007; T3: r = 0.80, P = 0.0008). EMG power did not correlate with high frequency EEG or attachment. Attachment styles are important trait-like factors shaping psychological vulnerability. Our result suggest that attachment dependence (low avoidance) is characterized by enhanced omega EEG activity, which could be interpreted as a heightened emotional arousal expressing itself during the state of REM sleep. Our findings emphasize the importance of extending the upper frequency limits of human EEG analysis. |